// SPDX-License-Identifier: GPL-2.0-or-later /* * G8BPQ compatible "AX.25 via ethernet" driver release 004 * * This code REQUIRES 2.0.0 or higher/ NET3.029 * * This is a "pseudo" network driver to allow AX.25 over Ethernet * using G8BPQ encapsulation. It has been extracted from the protocol * implementation because * * - things got unreadable within the protocol stack * - to cure the protocol stack from "feature-ism" * - a protocol implementation shouldn't need to know on * which hardware it is running * - user-level programs like the AX.25 utilities shouldn't * need to know about the hardware. * - IP over ethernet encapsulated AX.25 was impossible * - rxecho.c did not work * - to have room for extensions * - it just deserves to "live" as an own driver * * This driver can use any ethernet destination address, and can be * limited to accept frames from one dedicated ethernet card only. * * Note that the driver sets up the BPQ devices automagically on * startup or (if started before the "insmod" of an ethernet device) * on "ifconfig up". It hopefully will remove the BPQ on "rmmod"ing * the ethernet device (in fact: as soon as another ethernet or bpq * device gets "ifconfig"ured). * * I have heard that several people are thinking of experiments * with highspeed packet radio using existing ethernet cards. * Well, this driver is prepared for this purpose, just add * your tx key control and a txdelay / tailtime algorithm, * probably some buffering, and /voila/... * * History * BPQ 001 Joerg(DL1BKE) Extracted BPQ code from AX.25 * protocol stack and added my own * yet existing patches * BPQ 002 Joerg(DL1BKE) Scan network device list on * startup. * BPQ 003 Joerg(DL1BKE) Ethernet destination address * and accepted source address * can be configured by an ioctl() * call. * Fixed to match Linux networking * changes - 2.1.15. * BPQ 004 Joerg(DL1BKE) Fixed to not lock up on ifconfig. */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include static const char banner[] __initconst = KERN_INFO \ "AX.25: bpqether driver version 004\n"; static int bpq_rcv(struct sk_buff *, struct net_device *, struct packet_type *, struct net_device *); static int bpq_device_event(struct notifier_block *, unsigned long, void *); static struct packet_type bpq_packet_type __read_mostly = { .type = cpu_to_be16(ETH_P_BPQ), .func = bpq_rcv, }; static struct notifier_block bpq_dev_notifier = { .notifier_call = bpq_device_event, }; struct bpqdev { struct list_head bpq_list; /* list of bpq devices chain */ struct net_device *ethdev; /* link to ethernet device */ struct net_device *axdev; /* bpq device (bpq#) */ char dest_addr[6]; /* ether destination address */ char acpt_addr[6]; /* accept ether frames from this address only */ }; static LIST_HEAD(bpq_devices); /* * bpqether network devices are paired with ethernet devices below them, so * form a special "super class" of normal ethernet devices; split their locks * off into a separate class since they always nest. */ static struct lock_class_key bpq_netdev_xmit_lock_key; static struct lock_class_key bpq_netdev_addr_lock_key; static void bpq_set_lockdep_class_one(struct net_device *dev, struct netdev_queue *txq, void *_unused) { lockdep_set_class(&txq->_xmit_lock, &bpq_netdev_xmit_lock_key); } static void bpq_set_lockdep_class(struct net_device *dev) { lockdep_set_class(&dev->addr_list_lock, &bpq_netdev_addr_lock_key); netdev_for_each_tx_queue(dev, bpq_set_lockdep_class_one, NULL); } /* ------------------------------------------------------------------------ */ /* * Get the ethernet device for a BPQ device */ static inline struct net_device *bpq_get_ether_dev(struct net_device *dev) { struct bpqdev *bpq = netdev_priv(dev); return bpq ? bpq->ethdev : NULL; } /* * Get the BPQ device for the ethernet device */ static inline struct net_device *bpq_get_ax25_dev(struct net_device *dev) { struct bpqdev *bpq; list_for_each_entry_rcu(bpq, &bpq_devices, bpq_list, lockdep_rtnl_is_held()) { if (bpq->ethdev == dev) return bpq->axdev; } return NULL; } static inline int dev_is_ethdev(struct net_device *dev) { return dev->type == ARPHRD_ETHER && strncmp(dev->name, "dummy", 5); } /* ------------------------------------------------------------------------ */ /* * Receive an AX.25 frame via an ethernet interface. */ static int bpq_rcv(struct sk_buff *skb, struct net_device *dev, struct packet_type *ptype, struct net_device *orig_dev) { int len; char * ptr; struct ethhdr *eth; struct bpqdev *bpq; if (!net_eq(dev_net(dev), &init_net)) goto drop; if ((skb = skb_share_check(skb, GFP_ATOMIC)) == NULL) return NET_RX_DROP; if (!pskb_may_pull(skb, sizeof(struct ethhdr))) goto drop; rcu_read_lock(); dev = bpq_get_ax25_dev(dev); if (dev == NULL || !netif_running(dev)) goto drop_unlock; /* * if we want to accept frames from just one ethernet device * we check the source address of the sender. */ bpq = netdev_priv(dev); eth = eth_hdr(skb); if (!(bpq->acpt_addr[0] & 0x01) && !ether_addr_equal(eth->h_source, bpq->acpt_addr)) goto drop_unlock; if (skb_cow(skb, sizeof(struct ethhdr))) goto drop_unlock; len = skb->data[0] + skb->data[1] * 256 - 5; skb_pull(skb, 2); /* Remove the length bytes */ skb_trim(skb, len); /* Set the length of the data */ dev->stats.rx_packets++; dev->stats.rx_bytes += len; ptr = skb_push(skb, 1); *ptr = 0; skb->protocol = ax25_type_trans(skb, dev); netif_rx(skb); unlock: rcu_read_unlock(); return 0; drop_unlock: kfree_skb(skb); goto unlock; drop: kfree_skb(skb); return 0; } /* * Send an AX.25 frame via an ethernet interface */ static netdev_tx_t bpq_xmit(struct sk_buff *skb, struct net_device *dev) { unsigned char *ptr; struct bpqdev *bpq; struct net_device *orig_dev; int size; if (skb->protocol == htons(ETH_P_IP)) return ax25_ip_xmit(skb); /* * Just to be *really* sure not to send anything if the interface * is down, the ethernet device may have gone. */ if (!netif_running(dev)) { kfree_skb(skb); return NETDEV_TX_OK; } skb_pull(skb, 1); /* Drop KISS byte */ size = skb->len; /* * We're about to mess with the skb which may still shared with the * generic networking code so unshare and ensure it's got enough * space for the BPQ headers. */ if (skb_cow(skb, AX25_BPQ_HEADER_LEN)) { if (net_ratelimit()) pr_err("bpqether: out of memory\n"); kfree_skb(skb); return NETDEV_TX_OK; } ptr = skb_push(skb, 2); /* Make space for length */ *ptr++ = (size + 5) % 256; *ptr++ = (size + 5) / 256; bpq = netdev_priv(dev); orig_dev = dev; if ((dev = bpq_get_ether_dev(dev)) == NULL) { orig_dev->stats.tx_dropped++; kfree_skb(skb); return NETDEV_TX_OK; } skb->protocol = ax25_type_trans(skb, dev); skb_reset_network_header(skb); dev_hard_header(skb, dev, ETH_P_BPQ, bpq->dest_addr, NULL, 0); dev->stats.tx_packets++; dev->stats.tx_bytes+=skb->len; dev_queue_xmit(skb); netif_wake_queue(dev); return NETDEV_TX_OK; } /* * Set AX.25 callsign */ static int bpq_set_mac_address(struct net_device *dev, void *addr) { struct sockaddr *sa = (struct sockaddr *)addr; memcpy(dev->dev_addr, sa->sa_data, dev->addr_len); return 0; } /* Ioctl commands * * SIOCSBPQETHOPT reserved for enhancements * SIOCSBPQETHADDR set the destination and accepted * source ethernet address (broadcast * or multicast: accept all) */ static int bpq_ioctl(struct net_device *dev, struct ifreq *ifr, int cmd) { struct bpq_ethaddr __user *ethaddr = ifr->ifr_data; struct bpqdev *bpq = netdev_priv(dev); struct bpq_req req; if (!capable(CAP_NET_ADMIN)) return -EPERM; switch (cmd) { case SIOCSBPQETHOPT: if (copy_from_user(&req, ifr->ifr_data, sizeof(struct bpq_req))) return -EFAULT; switch (req.cmd) { case SIOCGBPQETHPARAM: case SIOCSBPQETHPARAM: default: return -EINVAL; } break; case SIOCSBPQETHADDR: if (copy_from_user(bpq->dest_addr, ethaddr->destination, ETH_ALEN)) return -EFAULT; if (copy_from_user(bpq->acpt_addr, ethaddr->accept, ETH_ALEN)) return -EFAULT; break; default: return -EINVAL; } return 0; } /* * open/close a device */ static int bpq_open(struct net_device *dev) { netif_start_queue(dev); return 0; } static int bpq_close(struct net_device *dev) { netif_stop_queue(dev); return 0; } /* ------------------------------------------------------------------------ */ /* * Proc filesystem */ static void *bpq_seq_start(struct seq_file *seq, loff_t *pos) __acquires(RCU) { int i = 1; struct bpqdev *bpqdev; rcu_read_lock(); if (*pos == 0) return SEQ_START_TOKEN; list_for_each_entry_rcu(bpqdev, &bpq_devices, bpq_list) { if (i == *pos) return bpqdev; } return NULL; } static void *bpq_seq_next(struct seq_file *seq, void *v, loff_t *pos) { struct list_head *p; struct bpqdev *bpqdev = v; ++*pos; if (v == SEQ_START_TOKEN) p = rcu_dereference(list_next_rcu(&bpq_devices)); else p = rcu_dereference(list_next_rcu(&bpqdev->bpq_list)); return (p == &bpq_devices) ? NULL : list_entry(p, struct bpqdev, bpq_list); } static void bpq_seq_stop(struct seq_file *seq, void *v) __releases(RCU) { rcu_read_unlock(); } static int bpq_seq_show(struct seq_file *seq, void *v) { if (v == SEQ_START_TOKEN) seq_puts(seq, "dev ether destination accept from\n"); else { const struct bpqdev *bpqdev = v; seq_printf(seq, "%-5s %-10s %pM ", bpqdev->axdev->name, bpqdev->ethdev->name, bpqdev->dest_addr); if (is_multicast_ether_addr(bpqdev->acpt_addr)) seq_printf(seq, "*\n"); else seq_printf(seq, "%pM\n", bpqdev->acpt_addr); } return 0; } static const struct seq_operations bpq_seqops = { .start = bpq_seq_start, .next = bpq_seq_next, .stop = bpq_seq_stop, .show = bpq_seq_show, }; /* ------------------------------------------------------------------------ */ static const struct net_device_ops bpq_netdev_ops = { .ndo_open = bpq_open, .ndo_stop = bpq_close, .ndo_start_xmit = bpq_xmit, .ndo_set_mac_address = bpq_set_mac_address, .ndo_do_ioctl = bpq_ioctl, }; static void bpq_setup(struct net_device *dev) { dev->netdev_ops = &bpq_netdev_ops; dev->needs_free_netdev = true; memcpy(dev->broadcast, &ax25_bcast, AX25_ADDR_LEN); memcpy(dev->dev_addr, &ax25_defaddr, AX25_ADDR_LEN); dev->flags = 0; dev->features = NETIF_F_LLTX; /* Allow recursion */ #if IS_ENABLED(CONFIG_AX25) dev->header_ops = &ax25_header_ops; #endif dev->type = ARPHRD_AX25; dev->hard_header_len = AX25_MAX_HEADER_LEN + AX25_BPQ_HEADER_LEN; dev->mtu = AX25_DEF_PACLEN; dev->addr_len = AX25_ADDR_LEN; } /* * Setup a new device. */ static int bpq_new_device(struct net_device *edev) { int err; struct net_device *ndev; struct bpqdev *bpq; ndev = alloc_netdev(sizeof(struct bpqdev), "bpq%d", NET_NAME_UNKNOWN, bpq_setup); if (!ndev) return -ENOMEM; bpq = netdev_priv(ndev); dev_hold(edev); bpq->ethdev = edev; bpq->axdev = ndev; eth_broadcast_addr(bpq->dest_addr); eth_broadcast_addr(bpq->acpt_addr); err = register_netdevice(ndev); if (err) goto error; bpq_set_lockdep_class(ndev); /* List protected by RTNL */ list_add_rcu(&bpq->bpq_list, &bpq_devices); return 0; error: dev_put(edev); free_netdev(ndev); return err; } static void bpq_free_device(struct net_device *ndev) { struct bpqdev *bpq = netdev_priv(ndev); dev_put(bpq->ethdev); list_del_rcu(&bpq->bpq_list); unregister_netdevice(ndev); } /* * Handle device status changes. */ static int bpq_device_event(struct notifier_block *this, unsigned long event, void *ptr) { struct net_device *dev = netdev_notifier_info_to_dev(ptr); if (!net_eq(dev_net(dev), &init_net)) return NOTIFY_DONE; if (!dev_is_ethdev(dev) && !bpq_get_ax25_dev(dev)) return NOTIFY_DONE; switch (event) { case NETDEV_UP: /* new ethernet device -> new BPQ interface */ if (bpq_get_ax25_dev(dev) == NULL) bpq_new_device(dev); break; case NETDEV_DOWN: /* ethernet device closed -> close BPQ interface */ if ((dev = bpq_get_ax25_dev(dev)) != NULL) dev_close(dev); break; case NETDEV_UNREGISTER: /* ethernet device removed -> free BPQ interface */ if ((dev = bpq_get_ax25_dev(dev)) != NULL) bpq_free_device(dev); break; default: break; } return NOTIFY_DONE; } /* ------------------------------------------------------------------------ */ /* * Initialize driver. To be called from af_ax25 if not compiled as a * module */ static int __init bpq_init_driver(void) { #ifdef CONFIG_PROC_FS if (!proc_create_seq("bpqether", 0444, init_net.proc_net, &bpq_seqops)) { printk(KERN_ERR "bpq: cannot create /proc/net/bpqether entry.\n"); return -ENOENT; } #endif /* CONFIG_PROC_FS */ dev_add_pack(&bpq_packet_type); register_netdevice_notifier(&bpq_dev_notifier); printk(banner); return 0; } static void __exit bpq_cleanup_driver(void) { struct bpqdev *bpq; dev_remove_pack(&bpq_packet_type); unregister_netdevice_notifier(&bpq_dev_notifier); remove_proc_entry("bpqether", init_net.proc_net); rtnl_lock(); while (!list_empty(&bpq_devices)) { bpq = list_entry(bpq_devices.next, struct bpqdev, bpq_list); bpq_free_device(bpq->axdev); } rtnl_unlock(); } MODULE_AUTHOR("Joerg Reuter DL1BKE "); MODULE_DESCRIPTION("Transmit and receive AX.25 packets over Ethernet"); MODULE_LICENSE("GPL"); module_init(bpq_init_driver); module_exit(bpq_cleanup_driver);